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xvii                      THE POTTO AND ANGWANTIBO                     547
" is not a happy one, for it is continually seeing ghosts; and that
is why it hides its face in its hands ! "
Thİ genus Perodicticus contains two quite recognisable species,
known respectively as the Angwantibo and Bosnian's Potto. The
former has been regarded as referable to a distinct genus, A.rcto-
cebus. A curious internal character of the Potto which is visible,
or at least can be felt, externally, is the long neural processes of
the cervical vertebrae, which project beyond the level of the skin.
The index finger is rudimentary and so is the tail, being only
just visible (about an inch in length) in the Potto. The colour
of both genera is a reddish grey, redder in the Potto. The
incisors are equal and minute. Both species are confined In
their range to West Africa, and are arboreal like the other
members of the sub-family. The Potto seems to share the
leisurely mode of progression of its Asiatic relatives, if Bosnian,
its original describer, is to be trusted. He says : " By the negroes
called Poo to, but known to us "by the name of Sluggard, doubtless
from its lazy, sluggish nature ; a whole day being little enough
for it to advance ten steps forward." The same writer did not
at all appreciate his addition to zoological knowledge, for he
remarked that the Potto " hath nothing very particular but his
odious ugliness." The Angwantibo is rare and but little known.
Our knowledge of its anatomy is derived from a paper by
Huxley.1 It is an animal measuring about 10^- inches in total
length to the end of the tail, which is only a quarter of an inch
long. The hands and feet are smaller than those of Perodicticus.
The index finger is rudimentary and has but two phalanges, and
it has no trace of a nail. In this it agrees with the Potto, but
" the spinous processes of the cervical vertebrae do not project in
the manner described by van der Hoeven in the Potto, though
they can be readily felt through the skin." The dental formula
of this genus as of the last is I -f C -J- Pm f- M f. The last lower
molar has a fifth cusp, which IB wanting in. the Potto. The last
upper molar is tricuspid. It is "bicuspid in the Potto. It seems
impossible to avoid agreeing with Professor Huxley that the
Angwantibo is entitled to generic separation.
The genus Loris also contains but a single species, L. gracilis,
and is, as its name denotes, an animal of more slender build than
the Slow Loris. Its eyes are very large, and the limbs excessively
1 "On tlie Aagwantibo/' JProc* Zool. JStcc. 1864, p. 314,